Acetylene manufacture



Dec. 28, 1954 JQL. BILLS ACETYLENE MANUFACTURE 2 Sheets-Sheet 2 Filed Sept. 9, 1949 a x a m C %4 /M ou w J United States Patent ACETYLENE MAN UFACTURE John L. Bills, Long Beach, Calif., assignor to Union Oil Company of California, Los Angeles, Calif., a corporation of California Application September 9, 1949, Serial No. 114,719

Claims. (Cl. 260-679) This invention relates to the manufacture of acetylene, and in particular concerns an improved process for obtaining acetylene by the partial oxidaton of saturated hydrocarbons.

It is known that acetylene may be obtained by the partial oxidaton of hydrocarbons, particularly saturated r aliphatic hydrocarbons such as methane, ethane, natural gas, etc., with oxygen or an oxygen-containing gas such as air. Such oxidation, however, does not occur to any significant extent except at elevated temperatures which favor a variety of side reactions, and consequently the yields of acetylene realized are far below theoretical; When air is employed as the oxidizing agent the yield of acetylene is even further reduced as a result of the diluent etfect of the large quantity of inert nitrogen present. Accordingly, the best yields of acetylene have been obtained by employing pure oxygen as the oxidizing agent and, even so, have not amounted to more than about 40 per cent, based on the amount of hydrocarbon consumed in the reaction. Such low yield and the high cost of the pure oxygen required, particularly the latter, have up to the present rendered the process commercially impractical despite the availability of large quantities of suitable saturated hydrocarbons in the form of natural gas, waste refinery gases, etc.

It is accordingly an object of the present invention to provide an improved process for the production of acetylene by the partial oxidation of hydrocarbons.

Another object is to provide a process whereby acetylene may be produced from saturated hydrocarbons in yields higher than those attained heretofore.

A further object is to provide a process whereby saturated hydrocarbons are caused to react with air to form acetylene in yields as good or better than those heretofore realized in processes employing relatively pure oxygen as the oxidizing agent.

Other objects will be apparent from the following detailed description of the invention, and various advantages not specifically referred to herein will occur to those skilled in the art upon employment of the invention in practice.

I have now found that the above and related objects may be realized in a process whereby hydrogen is added to a reactant gas mixture comprising a hydrocarbon and oxygen while said mixture is undergoing reaction at a high temperature over a short period of time. More particularly, I have found that acetylene may be produced in relatively high yields by passing a gaseous mixture consisting essentially of a hydrocarbon, particularly a .saturated aliphatic hydrocarbon such as methane or natural gas, and oxygen or an oxygen-containing gas 'through a reaction zone maintained at an acetylene' producing temperature, e. g., between about 1100 and about l500 C., at such a rate that the time of passage through the reaction zone is between about 0.005 and about 0.02 seconds, and simultaneously adding hydrogen to the reactant gas stream at a point intermediate along the length of the reaction Zone. I am aware that it has been proposed to add hydrogen to a similar reactant gas mixture prior to its passage through a high temperature reaction zone, but I have found that such procedure does not attain the advantageous results secured by adding the hydrogen to the reactant mixture during the course of the reaction, i. e., after the reaction has become initiated within the reaction zone. Furthermore, I have found that there is an optmum point for the addition of the hydrogen during the reaction, whereby maximum Z,698,349 Patented Dec. 28, 1954 yields of acetylene `are obtained. The location of such point depends primarily upon the reaction time, i. e., upon the time of passage of the reactant gas mixture through the reaction zone, although other factors are involved ,to a lesser extent, and accordingly is best expressed in terms of time. In general, highest yields of acetylene are obtained when the hydrogen is added to the reactant gas mixture after the elapse of from about 25 to about per cent of the total reaction time. In most nstances such period of time amounts to between about 0.002 and about 0.015 second.

The invention thus consists in a process whereby a reactant gas mixture essentially comprising a hydrocarbon and oxygen is subjected to an acetylene-producing temperature for from about 0.005 to about 0.02 second, during which time hydrogen is added to the mixture, preferably after the elapse of from about 25 to about 75 per cent of the total reaction time. In addition to producing acetylene in yields considerably higher than those realized in previous processes, such procedure is further advantageous in that it completely eliminates the formation of free carbon as one of the products of the reaction. Furthermore, the reactions involved when employing the present procedure are more highly exothermic than those 'of the previously known processes, and accordingly the heat requirements of the present process are substantially lower. Also, the production of carbon dioxide as a by-product is markedly decreased.

The nature of the invention may be readily understood by reference to the acco'mpanying drawings which form a part of this specification. In said drawings, Figure 1 diagrammatically represents a longitudinal cross-section of a simple apparatus which has been experimentally employed to demonstrate the nature of the invention. Figure 2 represents a longitudinal cross-section of a somewhat different form of apparatus which may be employed in practicing the invention. Figura 3 graphically illustrates the relationship which exists between the yield of acetylene and the point of hydrogen addition employing reactors similar to those illustrated by Figures 1 and 2 under certain Operating conditions more fully described hereinafter.

Referring now to Figure 1, the illustrated apparatus consists simply of a quartz tube 1.0 fitted at point 11 along its length with a side-arm 12. Beyond point 11, tube 10 is enlarged to about twice its initial diameter. The tube and side-arm assembly is movably supported in furnace 13 in such manner that it may be moved horizontally with respect thereto. Furnace 13 is provided with electrical heating means, shown as a heating coil 14, capable of providing a high temperature within tube 10. The extent of the heating means along the length of tube 10 for practical purposes defines a reaction zone A within tube 10. A gaseous mixture of hydrocarbon and oxygen or air is introduced into tube 10 and hydrogen is introduced into the side arm 12. Within tube 10 the reaction mixture passes through reaction zone A within which, at point 11, it is joined by the stream of hydrogen introduced into side-arm 12. It will be seen that by moving the tube and side-arm assembly in and out of the furnace 13, the point at which hydrogen is added to the reactant gas may be varied with respect to the reaction Zone A so that the hydrogen may be added to the reactant gas at any time during its passage through the reaction zone. The product gases withdrawn from the enlarged portion of tube 10 are passed to a product recovery system, not shown.

The following example typifies experiments carried out with the apparatus of Figure l to demonstrate the eect of adding hydrogen to the reactant gas mixture at different points along the reaction zone.

Example I The reactor was constructed substantially as shown in Figure l, the narrow portion of tube 10 and side-arm 12 each having an inside diameter of about /3 nch, and the enlarged portion of tube 10 having a diameter of about /4 inch. The heating element was regulated to maintain a temperature of about l200 C. along an 8- inch length of tube 10, thereby providing a reaction zone 8 inches long; The feed gas, consisting-*of 24.6 per cent :by volurne of methane and 75.4 per cent by Volume of air, amountng to a mole ratio of methaneto oxygen of about 1.63/1, was introduced into the reactor at a rate of 7.94 s. c. f./hr., and hydrogen was introduced into the sidearmxat a rate of 389 s. c; f;/hr. :The-male ratioofi hydrogen to methanewasabout 2/ 1. The-reaction; products wtihdrawn from the ;reactor -were immediately cooled,

, passed through a cold trap' to knock out condensible prod- I ucts, :and the non-condensed gaswas; thence: collected' for `analysis in a gas sampling system. A'series ofi fivesexperiments Was carried out under'theserconditions, the point of hydrogen addition along the length:of the reaction .zone-being variedin each case by moving thetube and side-arm .assembly along thelength ofthefurnace. 'The data obtained are tabulated 'as follows:

Point of Hz Tineof Hz Time of Hz Acetylene Experiment Addtion, Addition, fAddition, vYield,

Inch'es n sec Perecnt e Percent d Distance in ches from beginning of the reaction zone.

b Time in seconds after entry of the feed gas into the reaction zone.

0 Percent of total reaction time elapsed before the addition ot hydrogen. d Based on amount ot methane consumed.

It will be noted that a significant improvement in the` yield of acetylene is effected by addinghydrogen to the reactant gas stream within the reactionszone 'after theelapse of ;only 5.3 per cent of 'the total-reaction time, amounting to about-0.0007 second, and that the maximum'yeld of acetylene was obtained by adding thehydrogen after the elapselof about 40 per cent of thestotal reaction time, .amounting to about 0.003 second.

While the apparatus and procedure described in the preceding example satisfactorily-illustrate the principle upon which the invention isbased, l have found that the yield of acetylene obtained-is'improved by employing a .-reactor which is better` adaptedto promoternon-turbulent mixing oflthe hydrogen andthe reactant. gas at the' point of hydrogen addition, and also to romote laminar fiow of the mixture of hydrogen and-.reactant gas'beyond the point of hvdrogen addition. Such ,a reactor is illustrated by Figure 2 of the accompanying drawings reference to which is now made. Said reactor-*consists of a quartz tube 21 having aconstrictedportion 22 .which forms an elongated reaction zone. Saidreaction zone may be heated to a high temperature by passing an -electric current through heating element23. An insulating layer 24 covers the heating element 23 and-mnimizes heat losses to the .atmosphere. A stopper 25 closes the open 'end of tube 2l-and serves tosupportfeed gas inlet 26 which is concentrically positioned within tube 21 and extends into the:reaction zone 22. By slidinggas inlet 26 in and out of the stopper 25, itsextent into reaction zone 22 may be varied at will. Stopper'ZS 'also supports hydrogen inlets ,27 which extcnd into tube 21 but not into the reaction zone 22. A section of tube 21 is packed with an insulating material28 which serves to protect the stopper 25 from the heat as well as to provide additional support `for feed gas inlet 26 andhydrogen inlets 27. The remainder of tube 21 is packed with nickel gauzel29 which serves as a fiame arrestor. The reaction zone 22 leads directly to conventonal means, not shown,-for cooling and collecting the product gas. The operation of this apparatus will be readily understood when it is considered that that portion .of the feed gas inlet 26 which extends into the reaction zone 22 becomes heated to the temperature of the reaction zone and hence comprises part of the reaction zone. Accordingly, the feed gas introduced into inlet 26 begins to react as soon as it reaches the point where the inlet extends into the reaction zone. Reaction in the absence of added hydrogen continues until the reactant gas reaches the end of inlet 26, whereupon it becones mixed with hydrogen and the reaction continues in the presence of hydrogen throughout the remaining length of the reaction zone. By sliding the inlet tube in and out of stopper 25, the time interval between the start of the reaction within the inlet tube and the addition of the hydrogen *at the end of the inlettube may be varied 'as desired.

The following examples illustrate practice of the invention employng a reactor of the type-just describedbut are not to be construed as limiting the inventon:

Example Il The reactor was constructed substantially as shown in Fgure 2, except that heating of the reaction zone was accomplished by 'kilo-Bar silicon carbide heating elements rather than by a col of resistance wire. T he reaction zone was about 8 inches long and was maintained at a temperature of about l200 C. The feed gas inlet Was %s inch in diameter, and the constricted portion of tube 22 was A inch in diameter. The feed gas, consisting of about 24.6 per cent by Volume of methane and 75.4 per cent by Volume of air,'was introduced into the feed gas inlet at a rate of 7.94 s. c. f./hr., and hydrogen was introduced into the hydrogen inlets at arate of 3.89 s. c. f./hr. The. mole ratio of hydrogen to methane Was about 2/ l. The product gas withdrawn from the reactor was shock-cooled, passed through a cold trap, and thence to a` conventonal gas sampling system. A series of five runs was made under these conditions,'the point, and hence the time, at which hydrogen was added being varied 'by sliding the feed gas'inlet in and out of the stopper.

The data obtained are tabulated as follows:

Point of u Time of 'l me of Aeetp'lene .Run No. H? Ha Addi- H Addi' Yield,

tion See b Pcrcent d Inches u eent 0 0. O 0. 00 0. 00 31. 8 1. 5 0. 0010 9. 27 43.0 3. 0 0. 00190 19. l 47. 8 5. O 0. 00332 39. 7 53. 4 7. 0 0. 00464 73. 4 50. 4

a Distance in incbes from beginning of reaction zone.

b Time in seconds after entry of the feed gas into the reaction zone.

e Pereent of total reaction time elapsed before the addition of hydrogen. d Based on amount of methane consumed.

It will be:noted that the reaction conditions employed above were the same as those employed in Example I, and that with the exception of Run No. 2 the point of hydrogen addition in the respective runs in each example was lkewise the same. Accordingly, Exanples I and ll are comparable with respect to all variables except the apparatus employed.

The curves shown in Figure 3 of the accompanying drawings are plotted from the data obtained in Examples I and II, and illustrate the relationshp between the yield of acetylene and thepoint of hydrogen addition. Also, a -comparison of the two curves indicates the improved results obtained by employing a reactor which promotes non-turbulent mixing of the reactant gas and the added hydrogen. It will further be noted from these curves that the optimum point of hydrogen addition, corresponding to the maximum yield of acetylene, was substantially the same in both sets of experiments.

Example III The apparatus and procedure employed was the same as that described above in Example II. The Operating conditions were as follows:

Feed gas:

Methane 214% by vol.

Air 786% by vol. Rate of feed .0 s. c. f./hr. Rate of hydrogen addition 3.21 s. c. f./hr. Mole ratio, hydrogen to methane 3/1 Reaction temperature 1200 C. Total reaction time .0112 sec. Hydrogen added i 0.006l2 sec. after reactant gas entered reaction zone.

Per cent of total reaction time I y elapsed before adding hydrogen. 59.0 l

&698.849

The composition of the non-condensed portion of the product gas was as follows:

Per cent by Volume Total 100.0

The yield of acetylene based on the amount of methane introduced in the feed gas was 39.0 per cent. The yield of acetylene based on the amount of methane consumed in the reaction was 64.0 per cent. The net consumption of the added hydrogen was substantially zero.

In order to demonstrate that the improved yield of acetylene secured in the present process is due to some Chemical action of the added hydrogen rather than to some physical effect of an added gas regardless of its chemical identity, there was carried out an experiment wherein nitrogen was substtuted for the added hydrogen. The feed gas, consisting of 24.5 per cent by Volume of methane and 75.5 per cent by Volume of air, was introduced into the reactor at a rate of 5.67 s. c. f./hr. The nitrogen was introduced at a rate of 6.18 s. c. f./hr., corresponding to a nitrogen to methane ratio of 4.4/1, and mixed with the reactant gas in the reaction zone after about 17.7 per cent of the total reaction time had elapsed. A reaction temperature of 1200 C. was employed. The amount of acetylene in the product gas was substantially zero.

Similarly, in order to demonstrate that the improved results attained by the present process are not primarily due merely to the introduction of heat into the reactant gas by the added hydrogen, the apparatus was arranged so that the added hydrogen was preheated to the reaction temperature and then mixed with the reactant gas just as the latter entered the reaction zone. The yield of acetylene, based on the methane consumed, was only 34.2 per cent.

Finally, in order to demonstrate the eifect of omtting the added hydrogen entirely, a feed gas containing 21.6 per cent by Volume of methane and 78.4 per cent by Volume of air was passed through the reaction zone maintained at a temperature of 1200 C. at a rate of 2.5 s. c. f./hr., corresponding to a reaction time of 0.0163 sec. The yield of acetylene, based on the amount of methane consumed, was only 10.8 per cent.

Considering now the essential Operating variables in somewhat greater detail, the reactant gas consists essentially of a proportioned mixture of a hydrocarbon and oxygen. The hydrocarbon reactant is preferably a normally gaseous saturated aliphatic hydrocarbon, i. e., methane, ethane, or propane, although liquid saturated aliphatic hydrocarbons of higher molecular weight may be employed if desired. Also, hydrocarbons other than saturated aliphatic hydrocarbons, e. g., olefines, naphthenes, aromatics, etc., may be employed if desired. When employing a liqnid hydrocarbon reactant, means should be provided for vaporizing such liquid hydrocarbon prior to its introduction into the reaction zone in admxture with the oxygen reactant. For economic reasons, methane, particularly as it occurs in natural gas, is preferred. The oxygen reactant may be pure oxygen itself, oxygen-enriched air, ordinary air, or any other oxygen-containing gas. As previously stated, air s preferred by reason of its lack of cost, and it is one of the features of the present process that the results obtaned employing air are comparable or better than those of previous processes in which pure oxygen was employed. The mole ratio of hydrocarbon to oxygen in the reactant gas mixture may be varied between rather wide limits, but in order to suppress undesirable side reactions the hydrocarbon should be present in an amount not less than that required by theory for reaction with the amount of oxygen present to produce acetylene. When methane or natural gas is employed as the hydrocarbon reactant, the mole ratio of hydrocarbon to oxygen should be greater than about 1.33/ 1 and is suitably between about 1:33/1 and about 2.0/ 1, preferably between about 1.5/ 1 and 1.8/ 1. When the oxygen reactant is provided in `6 the form of air and the hydrocarbon reactant is methane or natural gas, the reactant gas may comprise from about 21 to about 30 per cent by Volume of the hydrocarbon and, correspondingly, from about 79 to about 70 per cent by Volume of air.

The amount of hydrogen added to the reactant gas during its passage through the reaction zone may likewise be varied considerably since there is at most only very little net Consumption 'of the added hydrogen in the reaction. Usually, however, it is preferred to add from about 0.5 to about 5 moles of hydrogen per mole of hydrocarbon in the reactant gas. v Such added hydrogen is advantageously preheated approxinately to the reaction temperature prior to its addition to the reactant gas within the reaction zone. In the reactors shown in Figures 1 and 2, such preheating of the added hydrogen is inherently provided by the design of the apparatus, particularly when the point of hydrogen addition is well within the reaction zone. However, independent means for preheating the hydrogen may be provided if desired.

The reaction temperature and the reaction time are more or less interdependent, shorter reaction times being employed at the higher reaction temperatures and vice versa. Ordinarily, the reaction temperature will be above about 1000 C., usually between about 1100 and about 1500 C., and the reaction time will vary from about 0.005 to about 0.02 second.

As is illustrated by the data obtaned in the experiments described in Examples I and II, above, and by the graphical presentation of these data in Figure 3 of the accompanying drawings, a substantial increase in the yield of acetylene may be obtaned by adding the hydrogen to the reactant gas within the reaction zone only a very short time after the entry of said gas into said zone. Also, some degree of improvement in acetylene yield is secured when the point of hydrogen addition is substantially at the end of the reaction zone, e., substantially at the end of the reaction period. Accordingly, the objects of the invention may be attained to a certain extent by adding the hydrogen to the reactant gas at any time during the course of the reaction, i. e., at any point along the length of the reaction zone. From a practical standpoint, the addition of hydrogen may advantageously be made after the elapse of from about 5 to about per cent of the total reaction time. The optimum time for the addition of the hydrogen, whereby maximum yields of acetylene are attained, depends upon the other Operating variables, e. g., the reaction temperature, the reaction time, the feed gas composition, etc. Ordinarly, however, such optimum time will be between about 25 and about 75 per cent of the total reaction time, i. e., highest yields of acetylene are usually attained when thehydrogen is added to the reactant gas mixture within the reaction zone after 25-75 per cent of the total reaction time has elapsed. Under the usual Operating conditions, such time amounts to between about 0.002 and about 0.015 second.

The advantage of employing a reactor which promotes non-turbulent mixing of the added hydrogen and the reactant gas is also apparent from the curves of Figure 3. Accordingly, it is preferred thatthe reactor employed be of such type. Such reactor may provide for the addition of hydrogen to the reactant gas stream in a direction concurrent with the flow of the latter, as is accomplished in the apparatus illustrated by Figure 2. Alternatively, the stream of added hydrogen may be tangentially introduced into the reactant gas stream. Other means of securing non-turbulent mixing of gas streams are known in the art;

As will be apparent to those skilled in the art, many variations with respect to the different Operating variables, reactor design, etc., are possible within the herein defined scope of the invention, and various engineering techniques may be applied to the practice of the invention on a large scale. Thus, for example, it may be desired to preheat the feed gas by heat exchange against the hot product gas or by other means. Similarly, various forms of heating equipment may be employed to provide the required high reaction temperature, and the reactor may take various forms adapted to conserve heat as much as possible, and may be constructed of various refractory materials. Likewise, the product gas may be treated in various known ways to separate the different constituents thereof. For example, the unreacted hydrocarbon and hydrogen may be recovered for re-use in the peroxide at anelevatedtemperature to obtain a -gas mix turescomprising the hydrocarbon andtoxygen, and the barium oxideproduced by suchtreatment issubsequent-` ly contacted with. air. atuan elevated temperature to regeneratetheperoxide for re-use in theprocess. v

The principle upon which the present invention is basedimay also be applied to the partial oxidation of hydrocarbons to `form olefines, vi..e., improved yields of olefines may be obtained' by adding hydrogen to aproportioned mixture of hydrocarbon and oxygen undergoing reactionto form olefines at: a high temperature over: a short period of time in the known manner. Similarly, in the high temperature reaction between a hydrocarbon; oxygen and amrnonia to producehydrogen cyanide, improved yields of the latter may be obtained by adding the ammonia reactant some time after introduction'of the hydrocarbon and oxygen-into the high tem perature reaction zone.

Other modes of applying the principle, of my invention may be employed instead of` those-explained, change being made as regards the materials-and apparatus employed, provided the step or steps stated by any of the following claims, or the equivalent of such statedstep or steps be employed.

I, therefore, particularly point out and distinctly claim asmy invention:

1. A- process of producing acetylene which comprises passing a reactant gas-mixture containing from about 21 to' about 30 per cent by Volume' of methane and from about 79 to about 70 per centby Volume of 'air through a reaction zone maintained at an acetylene-producing temperature between=about l100 C. and about 1500 C. at such a rate that the residence time of' said reactant gas mixture within said reaction zone is between about 0.005 and about 0.02 second, and simultaneously introdueing'a gas consisting of hydrogen into said reaction zone at such point along the lengththereof and n such manner that said hydrogen is substantially non-turbulently' mixed with said reactant gas mixture within said reaction zone after the elapse of from about to 'about 75 per cent of the total reaction time, said hydrogen having been preheated to a temperature substantially equal tothe temperature maintained within said reaction' zone prior to its introduction thereinto and sufiicient of said hydrogen being introduced into said reaction zone to provide from about 0.5 to about 5 moles of hydrogen per mole of methane present in said reaction zone.

2. In a process for the production of acetylenev wherein a reactant gas mixture essentially comprising hydrocarbon and oxygen is continuously passed through an elongated reaction zone maintained at an acetylene-producing temperature above about 1000" C. and within which an acetylene-producingreaction occurs, the step which comprises continuously admixing a gas consisting of`hydrogen'with the gases undergoing reaction within said zone after the start but before the completion of said reaction by introducing said stream of hydrogen into 8 said .reaction zonetat a point intermediate along ,thelength thereof.

3. In aprocess for the production of acetylene whereina reactant gas mixture essentially comprising a saturatedaliphatic hydrocarbonand oxygen' is continuously passed through an elongated reaction zone maintained at anacetylene-producingtemperature above about 1000 C. andwithin which anacetylene-producing reaction occurs, saidhydrocarbon being present in the reactant gasmixturein an amount at least equal tothat theoretically-required for reaction with the amount* of oxygen present to produce acetylene; and the rate of passage of said gas mixture through said reaction zone being such that the residence-time' of the' gas within the'reaction zone is between about 0.005 and about 0.02 second,vthe step which comprises continuously admixing a gas con-. ssting of hydrogen with the gases undergoing reaction within said zone after the start but before the completion of said reaction by introducing said stream of hydrogen into said reaction zone at a point intermediate along the length thereof.

4'. A process according to claim 3 in which the. reactant gas mixture essentially comprises methane, and oxygen in a mole ratio at least equal to about 1.33/1 and the reaction zone is maintained at an acetylene-produc: ing temperature between about 1100 C. and about 15001C.`

5. Aprocess-according to claim 3 wherein the hydrogen is preheated to a temperature substantially equal'to that maintained within the reaction zone prior to its introduction therento.

6. A process according to claim 3 wherein the amount of 'hydrogen introduced into the reaction zone is suf ficient to provide from about 0.5 to about S moles of hydrogen per mole of methane in the reactant gas..

7. Aprocess accordingto claim 3 wherein the: reactant gas mixture comprises from about 21 to about. 30 per cent by Volume of methane and from about 79 to about `per cent by Volume of air, and the. reaction zone. is maintained at a temperature between about` 1.100 C. and about 1500 C.

8..A.process accordingto claim 7 wherein the hydro gen is preheated to, &temperaturesubstantially equal to that maintained within the reaction zone prior, to.` its introduction therento.'

9-. A process according to claim 7 wherein the amount of-`hydrogen introduced into said reaction zone is suf ficient to provide from about 0.5 to about 5 moles of hydrogen per mole of methane in the reactant gas.

10. A process according to claim 7 wherein the hydrogen is introduced into the reaction zone at such'point that it is caused' to be admixed with the gases undergoing reaction within said zone 'after the-elap'se of from about 25 to about per cent of the total reaction time.-

Refereces Cited in thefile of this patent UNITED STATES PATENTS Number Name Date.

1,823,503 Mittasch et al Sept. 15, 1931 2,370,849. Dutcher Mar. 6, 1945 2,377,245 Krejci May 29, 1945 2,549,240 Robinson Apr. 17, 1951 FOREIGN PATENTS Number Country Date 479,438 Great Britain Feb.-`4, 1938 

1. A PROCESS OF PRODUCING ACETYLENE WHICH COMPRISES PASSING A REACTANT GAS MIXTURE CONTAINING FROM ABOUT 21 TO ABOUT 30 PERCENT BY VOLUME OF METHANE AND FROM ABOUT 79 TO ABOUT 70 PER CENT BY VOLUME OF AIR THROUGH A REACTION ZONE MAINTAINED AT AN ACETYLENE-PRODUCING TEMPERATURE BETWEEN ABOUT 1100* C. AND ABOUT 1500* C. AT SUCH A RATE THAT THE RESIDENCE TIME OF SAID REACTANT GAS MIXTURE WITHIN SAID REACTION ZONE IS BETWEEN ABOUT 0.005 AND ABOUT 0.02 SECOND, AND SIMULTANEOUSLY INTRODUCING A GAS CONSISTING OF HYDROGEN INTO SAID REACTION ZONE AT SUCH POINT ALONG THE LENGTH THEREOF AND IN SUCH MANNER THAT SAID HYDROGEN IS SUBSTANTIALLY NON-TURBULENT- 